The media was abuzz this week after an international group of researchers proposed that scientists may have been looking for the biological underpinnings of homosexuality in the wrong place. Although scientists have spent the last few decades scouring our genome for a “gay gene,” William Rice, Urban Friberg, and Sergey Gavrilets suggest in The Quarterly Review of Biology that homosexuality may have its roots in epigenetics, rather than in genetics.

According to the authors, much of we know about homosexuality suggests that it is not simply a result of direct genetic inheritance. First, despite thorough genome-wide research, no study has been able to find a gene or genetic marker that is consistently associated with homosexuality. Second, although twenty to fifty percent of the variation in sexual orientation appears to be inherited in some way, identical twins don’t necessarily share a sexual orientation; if one twin is gay, there’s only a twenty percent probability that the other twin is, too. This low probability (or “concordance”) suggests that simple genetic inheritance might not drive sexual orientation. Finally, the authors argue that any purely genetic “fitness-reducing phenotypes” like homosexuality would be selected against and weeded out of the gene pool.

What is epigenetics?

Most of the information we inherit is carried by the sequence of bases (A, T, C, and G) in DNA. But the DNA sequence doesn't explain everything; different cell types (like neural and liver cells, for example) share the same DNA but have distinct properties that are maintained as the cells divide.

These differences are typically maintained through differences in the proteins that package the DNA. They can be inherited, and they can hold the DNA in configurations that make it easier (or harder) for the proteins that manage the expression of genes to access the underlying sequence of bases. Although this form of epigenetic inheritance is key to the development of an organism, these changes are all wiped out during the formation of eggs and sperm, so they can't be inherited.

There's another, less-common form of epigenetic inheritance that involves a chemical modification of the bases themselves. This doesn't change the base pairing rules (A still pairs with T, G, with C). But it can change the way proteins interact with DNA, which will alter gene expression. The key difference with this form is that these chemical modifications can be transferred by the DNA of eggs and sperm, allowing them to influence the expression of genes in the next generation.

Rice, Friberg, and Gavrilets argue that epigenetics could theoretically play a role in sexual behavior via sex-specific epi-marks that affect androgen sensitivity. Under their hypothesis, female embryos would normally develop female-specific epi-marks which would decrease sensitivity to circulating testosterone and feminize the fetus. Male embryos, meanwhile, would gain male-specific epi-marks that would increase testosterone sensitivity and masculinize the developing fetus.

Normally, epi-marks are “erased” each generation, so they aren't usually passed along to offspring; however, in some instances, epi-marks can persist and be inherited by the next generation. The researchers argue that cross-sex epigenetic inheritance—either from mother-to-son or father-to-daughter—could contribute to homosexuality. A female-specific epi-mark that persisted in male offspring that inherited it would trigger feminization—and possibly sexual attraction to males. A similar scenario could happen if a male-specific epi-mark was inherited by a daughter, causing masculinization and, potentially, sexual attraction to other females.

By feminization of males and masculinization of females, the researchers are referring to “gonad-trait discordance,” which indicates that a person’s genitals and sexual preference aren’t in line with what is generally considered “normal.” The authors also cite two other androgen-influenced traits (cryptorchidism and hypospadias) that may be related to sex-specific epi-marks. However, “may” is the key word, since none of these hypotheses have been tested with real data.

In the end, that’s where the paper leaves us: with an untested hypothesis that appears to fit the statistical frequencies and inheritance patterns of homosexuality. The researchers use a mathematical formula to illustrate that this type of epigenetic inheritance could occur, but the paper is purely theoretical rather than data-driven, and it refers to remarkably few human studies.

This lack of human-related studies is one of the major criticisms of epigenetics today. As John Timmer explains, there’s very little evidence that epigenetic inheritance across generations plays a significant role in human behavior, at least for now.

There’s also little discussion in the paper of the spectrum of human sexual behavior, which ranges from those who engage solely in same-sex sexual encounters to those who simply like to experiment once in a while. The authors do, however, state that for the paper, the definition of homosexuality includes “any same-sex partner preference… including bisexuality.” And it doesn't deal at all with the fact that sexual preference is just one part of a large suite of behaviors that can be some combination of "masculine" and "feminine."

It’s important to see this paper as what it is—a theoretical possibility with a lot of unanswered questions—rather than a tested scientific conclusion. It’s easy for media outlets to overhype this type of untested hypothesis; some are already touting epigenetics as the "answer to homosexuality." The paper is also an easy target for outspoken activists, such as Bryan Fischer of the American Family Association, who is using the paper as anti-gay political fodder.

Homosexuality helps fish get girls

Another recent study also takes issue with one of Rice, Friberg, and Gavrilets’ claims—that homosexuality is necessarily a “fitness-reducing phenotype.” A recent study in Biology Letters suggests that, in some species, homosexual behavior can confer advantages in terms of reproductive success.

The researchers behind this experiment studied mollies (Poecilia mexicana), freshwater fish found in Mexico. Female mollies engage in what is called “mate choice copying,” meaning that they prefer to mate with males they have watched copulate with other females. Not only does this strategy make it easier for females to find mates, it also gives them clues about male quality.

But homosexual behavior among males is also common among mollies. This behavior, called “nipping,” occurs when a male nips at the genitals of another male. The researchers wondered if homosexual behavior would affect females’ preferences in the same way as heterosexual behavior does. Would seeing a male engage in nipping increase a female’s attraction to him?

There are two kinds of male mollies: dominant males, which are large and brightly colored, and subordinate males, which are small and drab in color. In both observations of natural behavior and in video playback tests conducted by the researchers, female mollies preferred dominant males to subordinate ones by a large margin.

However, video playback tests showed that the perceived attractiveness of subordinate males skyrocketed after females watched them engage in sexual behavior. In fact, this made such a difference that subordinate males that had been observed in a sexual interaction actually became preferable to dominant males that hadn't. Moreover, it didn’t matter whether males nipped at other males or copulated with females; engaging in any sexual behavior at all increased female preference for the males.

In nature, subordinate males are generally the ones engaging in homosexual nipping behavior. The researchers suggest that this behavior might be an alternative strategy: if less desirable males can’t get a boost in sexual attractiveness by actually mating, homosexual nipping behavior may be another way to get the girl. In this system, it appears that occasional homosexuality may actually increase fitness, at least for some males.

What it all means

It’s important to note that male mollies do not engage exclusively in homosexual behavior; in other words, males that nip at other males also mate with females. Exclusive homosexuality has only been recorded in a few species, such as humans, sheep, and some birds. It’s possible that the factors that drive these two types of homosexuality are quite different.

There have been studies of exclusive homosexuality in these species, and they have turned up some interesting information. We now know that the incidence of male exclusive homosexuality is about the same in humans and sheep, and that male sheep that engage exclusively in intercourse with other rams have different brain morphology and activity than male sheep that seek out sex with ewes. It has also been suggested (and demonstrated in some populations) that the female relatives of homosexual men have more offspring than those of straight men.

As Rice, Friberg, and Gavrilets note, the inheritance of homosexuality doesn’t appear to be as simple as a “gay gene.” But for now, we simply don’t know what factors contribute to homosexuality in humans or in most other species. While epigenetics may help us understand homosexuality one day, we’re not there yet.

Promoted Comments

It should probably be added that 23andMe, in response to a lot of requests, conducted a GWAS on homosexuality, which they presented at ASHG last month. Their sample was >24,000 participants but they were unable to find any significant associations between sexual orientation and SNPs.

154 Reader Comments

The argument that homosexuality should have been selected out of the gene pool doesn't really make sense to me. Assuming it is genetic, how do we know that the overall effect of the gene is a reduction in fitness? I can hypothesize a couple ways that homosexual individuals might make the tribe more fit by reducing their own personal fitness for example.

Amen (not a religious Amen, but amen). The fact that it hasn't been selected out amongst either thinking humans with unusual protection of those that are not 'the fittest' and perhaps less intelligent animals such as sheep suggest there are either very real advantages to homosexuality or it's not genetic. As a completely gay individual cannot pass on their genes, it would seem to suggest the latter.

Yes, many gay couples actually raise children (such as when lesbians bore them using a gay male friend). Those children have a 97% chance of being straight themselves-- about the same as the general population. If it was truly genetic you'd think it would be higher.

As a male who was sexually abused as child, by 3 different male perpetrators over the course of eight years, I can tell you first hand I am not gay.

My post was not to say that abuse automatically makes one gay. But to say that the science hasn't yet shown that it hasn't caused many people to go that route, and that science still considers it a possible factor for many people.

Orientation isn't about "going that route." It's not a behavior. Celibacy is a behavior. Promiscuity is a behavior. Orientation is being attracted to someone else. When you feel attracted to someone of the opposite sex, what caused you to "go that route?"

The biochemical reactions to trauma may affect people this way, to " go that route, down that biochemical pathway." Not all cases since we are talking bio systems. And every biologist knows that biology isn't like mathematics.

Your post is very eloquent, but I have read very little science that substantiates your position. What we do have is eyewitness accounts from gay folk who tell us they had no choice, they felt these attractions from earliest childhood (which is a little suspect to me as a developmental psychologist will tell you that it is normal for boys to want to be with boys and girls to want to be with girls until puberty hits so gays should not have known until they were in puberty. On every playground on the planet you can hear 7 year old boys calling girls gross and vice versa.)

Eyewitness accounts are not science, if they were people would believe those who saw Jesus resurrected, people would believe those who have near death experiences telling us that heaven is real.

I personally would lay down my life to stop the lynching of a gay man, I would step in front of the guy throwing the punches, i would speak out against bullying and foul treatment of homosexuals, but when it comes to science. I will not accept eyewitness accounts as fact. Humans can be deceived as so many here (including yourself) like to say about the religious.

As a male who was sexually abused as child, by 3 different male perpetrators over the course of eight years, I can tell you first hand I am not gay.

My post was not to say that abuse automatically makes one gay. But to say that the science hasn't yet shown that it hasn't caused many people to go that route, and that science still considers it a possible factor for many people.

Orientation isn't about "going that route." It's not a behavior. Celibacy is a behavior. Promiscuity is a behavior. Orientation is being attracted to someone else. When you feel attracted to someone of the opposite sex, what caused you to "go that route?"

The biochemical reactions to trauma may affect people this way, to " go that route, down that biochemical pathway." Not all cases since we are talking bio systems. And every biologist knows that biology isn't like mathematics.

Your post is very eloquent, but I have read very little science that substantiates your position. What we do have is eyewitness accounts from gay folk who tell us they had no choice, they felt these attractions from earliest childhood (which is a little suspect to me as a developmental psychologist will tell you that it is normal for boys to want to be with boys and girls to want to be with girls until puberty hits so gays should not have known until they were in puberty. On every playground on the planet you can hear 7 year old boys calling girls gross and vice versa.)

Eyewitness accounts are not science, if they were people would believe those who saw Jesus resurrected, people would believe those who have near death experiences telling us that heaven is real.

I personally would lay down my life to stop the lynching of a gay man, I would step in front of the guy throwing the punches, i would speak out against bullying and foul treatment of homosexuals, but when it comes to science. I will not accept eyewitness accounts as fact. Humans can be deceived as so many here (including yourself) like to say about the religious.

As a gay man I feel very uneasy about any research concerning the causes of homosexuality. I can't help thinking that it might funded by homophobic lobby in order to be able to eliminate homosexuality in the future generations.

On a less paranoid note, my homosexuality on it's own was never a cause of any problems for me - but homophobia of others was. Shouldn't that be the main target of any research instead?I tend to think of being gay as an equivalent of being left handed - a variant of the normal. And I don't think anyone would want to fix that, right?

P.S. Huh, "fitness-reducing phenotypes"? What a load of bollocks! Most gay men I know are much fitter than the straights.(I know, I know, not that kind of fitness - although frankly I do not agree with the intended meaning as well)

Why is bisexuality grouped with homosexuality? There are some like myself who really are attracted to both. If society didn't frown upom it, I'd have a girlfriend and boyfriend; husband and wife simultaneously. Really I think we all have at least a little of it in us.

This sounds like a desperate attempt to find something that may not even be there.

If the epigentics hypothesis turns out to be incorrect, will it become mandatory to simply believe it is biological, like creationist science?

Who initially decided it was biological, a scientist or a political activist? Did they also decided that other possibilities, like choice, or a combination, were inherently homophobic and politically incorrect?

And how does this account for bisexuality, asexuality or pansexuality? Do they have to be declared involuntary and linked to an unknown biological cause too?

Edit: I don't care about your political excuses or what the Christians are saying and how you have to take the opposite stance to spite them, political context doesn't change objective truth. I read over the other comments and it seems to be boiling down to that.

As a gay man I feel very uneasy about any research concerning the causes of homosexuality. I can't help thinking that it might funded by homophobic lobby in order to be able to eliminate homosexuality in the future generations.

On a less paranoid note, my homosexuality on it's own was never a cause of any problems for me - but homophobia of others was. Shouldn't that be the main target of any research instead?I tend to think of being gay as an equivalent of being left handed - a variant of the normal. And I don't think anyone would want to fix that, right?

I do not wish to be insensitive, but I can't help but draw a parallel between your attitude and the attitude of the religious who didn't like Copernicus looking into whether or not the Earth was the center of the universe. I don't like what science will say, so don't do the science. That is not a good road to go down.

I agree that society should put much effort into finding out how to combat those who gay-bash and attempt to do harm to homosexuals. I think good old fashioned morals are the solution - the golden rule, etc. However using labels like the homophobic lobby will add fuel to the fire instead of helping temper the coals. Peace.

Your post is very eloquent, but I have read very little science that substantiates your position.

I've linked to a well-cited resource from the experts in this thread already. I've also linked to a Wikipedia article with more citations. You've given us nothing except a characterization of the research that doesn't seem to fit.

Quote:

What we do have is eyewitness accounts from gay folk who tell us they had no choice, they felt these attractions from earliest childhood (which is a little suspect to me as a developmental psychologist will tell you that it is normal for boys to want to be with boys and girls to want to be with girls until puberty hits so gays should not have known until they were in puberty. On every playground on the planet you can hear 7 year old boys calling girls gross and vice versa.)

I really do not think you're describing the actual basis of the scientific literature. It doesn't match, for example, the studies that have formed the basis for my sources. When you say "I have read very little science that substantiates your position," what I think you mean is that you have read very little science on the subject, period. Perhaps you would care to substantiate your claim by pointing to the sources you've used to arrive at this conclusion? And I don't know about you, but to me the early childhood "girls have cooties!" mentality was vastly different from my current "Men are kind of a mood-killer. I want to put my penis in a lady" mentalities. But what do I know, that's just my "eyewitness account," right?

Donte wrote:

This sounds like a desperate attempt to find something that may not even be there.

It sounds like the preliminary stages of any scientific line of inquiry. Gather the evidence, come up with a plausible explanation that fits the data well and isn't obviously contradicted, find a way to test it against new data. If you remember from your elementary school science lessons you might recognize it as that whole observation -> hypothesis -> test process, to put it simply. This specific paper positing an epigenetic basis for orientation is at the second stage of that process.

Quote:

Who initially decided it was biological, a scientist or a political activist?

Nobody has determined that it's purely biological. Research is ongoing. What we pretty well have determined is that it's not a choice or a psychological disorder. We've basically eliminated those possibilities, through actual research.

Your post is very eloquent, but I have read very little science that substantiates your position.

I've linked to a well-cited resource from the experts in this thread already. I've also linked to a Wikipedia article with more citations. You've given us nothing except a characterization of the research that doesn't seem to fit.

Quote:

What we do have is eyewitness accounts from gay folk who tell us they had no choice, they felt these attractions from earliest childhood (which is a little suspect to me as a developmental psychologist will tell you that it is normal for boys to want to be with boys and girls to want to be with girls until puberty hits so gays should not have known until they were in puberty. On every playground on the planet you can hear 7 year old boys calling girls gross and vice versa.)

I really do not think you're describing the actual basis of the scientific literature. It doesn't match, for example, the studies that have formed the basis for my sources. When you say "I have read very little science that substantiates your position," what I think you mean is that you have read very little science on the subject, period. Perhaps you would care to substantiate your claim by pointing to the sources you've used to arrive at this conclusion? And I don't know about you, but to me the early childhood "girls have cooties!" mentality was vastly different from my current "Men are kind of a mood-killer. I want to put my penis in a lady" mentalities. But what do I know, that's just my "eyewitness account," right?

Donte wrote:

This sounds like a desperate attempt to find something that may not even be there.

It sounds like the preliminary stages of any scientific line of inquiry. Gather the evidence, come up with a plausible explanation that fits the data well and isn't obviously contradicted, find a way to test it against new data. If you remember from your elementary school science lessons you might recognize it as that whole observation -> hypothesis -> test process, to put it simply. This specific paper positing an epigenetic basis for orientation is at the second stage of that process.

Quote:

Who initially decided it was biological, a scientist or a political activist?

Nobody has determined that it's purely biological. Research is ongoing. What we pretty well have determined is that it's not a choice or a psychological disorder. We've basically eliminated those possibilities, through actual research.

Let's also remember that a "biological" cause for homosexuality, or any sexuality for that matter doesn't strictly mean "genetic". A human being is an amalgam of all sorts of biological mechanisms. Though these mechanisms at some point are grounded in genes, it doesn't necessarily take a "gay gene" to make someone so. As the authors of the paper have speculated, it may be something that causes hormones to be increased or decreased. Maybe these increases or decreases have to occur at a specific time in development to trigger homosexuality, or maybe it needs both and another environmental factor on top of that? Truth is if homosexuality has any root in any biological mechanism, from gene to protein to hormone to a synapse firing, then it can correctly be considered to be biological.

The only way being gay can be considered a "choice" is if all humans are in fact attracted to the opposite sex, that homosexuals choose to go against their natural attraction to the opposite sex, and then lie in large amounts claiming that isn't what they are doing. This idea of homosexuality occupies a narrow band in the spectrum of ideas that can cause homosexuality, does not include all of the empirical evidence, and makes quite a few assumptions itself.

This sounds like a desperate attempt to find something that may not even be there.

It sounds like the preliminary stages of any scientific line of inquiry. Gather the evidence, come up with a plausible explanation that fits the data well and isn't obviously contradicted, find a way to test it against new data. If you remember from your elementary school science lessons you might recognize it as that whole observation -> hypothesis -> test process, to put it simply. This specific paper positing an epigenetic basis for orientation is at the second stage of that process.

Wheels Of Confusion wrote:

If you remember from your elementary school science lessons

That's a nice, subtle ad hominem you have there, but in elementary school science the purpose of the experiment is to determine if the hypothesis is correct, which means you have to entertain the possibility that it is not, instead of modifying the experiment until it shows your desired outcome.

Current science shows that there is no conclusive biological cause that can be demonstrated, as of now it seems to simply hang on beliefs, beliefs which seem to of birthed the epigenetic hypothesis, and if it turns out to be incorrect, it will simply be replaced yet with another hypothesis in an attempt to prove it by other means.

The hypotheses themselves are not the problem, it is the political mentality that homosexuality, of all the sexual preferences, has to be considered pre-determined by default, until it is someday proven by any means necessary.

That's a nice, subtle ad hominem you have there, but in elementary school science the purpose of the experiment is to determine if the hypothesis is correct, which means you have to entertain the possibility that it is not, instead of modifying the experiment until it shows your desired outcome.

And?

Quote:

Current science shows that there is no conclusive biological cause that can be demonstrated, as of now it seems to simply hang on beliefs, beliefs which seem to of birthed the epigenetic hypothesis, and if it turns out to be incorrect, it will simply be replaced yet with another hypothesis in an attempt to prove it by other means.

It's not "simply out of belief." There are good reasons to attribute at least some of the influence on orientation to biology. Specific mechanisms (like SNPs, or the simplest genetic variations) have pretty much been ruled out, and some other mechanisms have been shown not to work. But not every possible biological factor has been, and at the same time the pattern of occurrence for homosexuality is not consistent with it being purely psychological, and definitely not consistent with it being a choice. Those possibilities have already been pretty thoroughly eliminated, unlike the myriad proposed biological factors. Now tell me, who is clinging to a belief in the face of evidence here?

I find it interesting that the researchers interpret the Mollies' genital nipping as homosexual behavior. It seems that the simpler and more likely explanation is that they're trying to prevent the rival from mating. A male with a damaged or irritated gonopodium would be less likely to breed successfully.

My thoughts too. For the Mollie fish it makes sense, even if they're not actually hurting the dominant fish, as doing so gives them a chance to reproduce as well. Human homosexuals, on the other hand, don't partake into homosexuality with the intent of reproduction. Comparing human sexuality with a Mollies' was kinda pointless really.

This sounds like a desperate attempt to find something that may not even be there.

It sounds like the preliminary stages of any scientific line of inquiry. Gather the evidence, come up with a plausible explanation that fits the data well and isn't obviously contradicted, find a way to test it against new data. If you remember from your elementary school science lessons you might recognize it as that whole observation -> hypothesis -> test process, to put it simply. This specific paper positing an epigenetic basis for orientation is at the second stage of that process.

Wheels Of Confusion wrote:

If you remember from your elementary school science lessons

That's a nice, subtle ad hominem you have there, but in elementary school science the purpose of the experiment is to determine if the hypothesis is correct, which means you have to entertain the possibility that it is not, instead of modifying the experiment until it shows your desired outcome.

Current science shows that there is no conclusive biological cause that can be demonstrated, as of now it seems to simply hang on beliefs, beliefs which seem to of birthed the epigenetic hypothesis, and if it turns out to be incorrect, it will simply be replaced yet with another hypothesis in an attempt to prove it by other means.

The hypotheses themselves are not the problem, it is the political mentality that homosexuality, of all the sexual preferences, has to be considered pre-determined by default, until it is someday proven by any means necessary.

In conclusion: political bigotry and science are incompatible.

Lack of evidence for one conclusion never actually lends support to a competing conclusion, especially when the competing conclusion lacks a lot of supporting evidence itself. We may not have found a specific biological mechanism that causes homosexuality, but this does not support the conclusion that homosexuals are choosing to be homosexual. Because homosexuality has become political there has been a lot of false-dichotomies created around it. In science you come to a conclusion by weighing what you do know (with supporting evidence) against what you don't know. We may not know the specific biological mechanism for homosexuality, but we do know a lot of people do not feel like they had any say in what their sexuality is which means that at least for a certain group of people homosexuality seems to be innate. Even if there is a group of people out there who felt like they chose their sexual identity, that doesn't negate the other group that felt they didn't choose. It doesn't necessarily need to be everyone chose or no one chose. It is entirely possible that some people chose they like one sex more than the other, and some people felt inherently attracted to the same sex. They are not inherently opposite. The reason homosexuality is considered to not be a choice is because most of the evidence points to that conclusion right now.

Im just wondering if the mollies nipping at the other male mollie's testicles is because by biting off or damaging their rival's testicles then those rivals wont be able to mate therefore reducing number of rivals.

Your post is very eloquent, but I have read very little science that substantiates your position. What we do have is eyewitness accounts from gay folk who tell us they had no choice, they felt these attractions from earliest childhood (which is a little suspect to me as a developmental psychologist will tell you that it is normal for boys to want to be with boys and girls to want to be with girls until puberty hits so gays should not have known until they were in puberty. On every playground on the planet you can hear 7 year old boys calling girls gross and vice versa.)

Oh, sexual attraction is present at a very young age, if I'm at all typical. I may not have wanted to play with girls in my age group when I was 7 or so, but that doesn't mean I wasn't attracted to them, or curious about them.

I think I was 5 or 6 when I found my dad's stash of Playboys, and the sexual response was immediate and intense, even if I didn't understand what the physical sensation meant. I can imagine there were a few little boys who had that response when they saw pictures of men.

IIRC, that self-segregation is a way of maximizing sexual attraction to non-siblings; boys and girls who live together during that period tend to not be sexually attracted to each other later on (hetero- or homosexually).

Im just wondering if the mollies nipping at the other male mollie's testicles is because by biting off or damaging their rival's testicles then those rivals wont be able to mate therefore reducing number of rivals.

Wouldn't work that way, a male mollie's "genitals" are a modified anal fin that acts as a tube during mating.

That's a nice, subtle ad hominem you have there, but in elementary school science the purpose of the experiment is to determine if the hypothesis is correct, which means you have to entertain the possibility that it is not, instead of modifying the experiment until it shows your desired outcome.

And?

Quote:

Current science shows that there is no conclusive biological cause that can be demonstrated, as of now it seems to simply hang on beliefs, beliefs which seem to of birthed the epigenetic hypothesis, and if it turns out to be incorrect, it will simply be replaced yet with another hypothesis in an attempt to prove it by other means.

It's not "simply out of belief." There are good reasons to attribute at least some of the influence on orientation to biology. Specific mechanisms (like SNPs, or the simplest genetic variations) have pretty much been ruled out, and some other mechanisms have been shown not to work. But not every possible biological factor has been, and at the same time the pattern of occurrence for homosexuality is not consistent with it being purely psychological, and definitely not consistent with it being a choice. Those possibilities have already been pretty thoroughly eliminated, unlike the myriad proposed biological factors. Now tell me, who is clinging to a belief in the face of evidence here?

Burden of proof fallacy, Your logic is that it is, by default, biological until every possibility is ruled out and that all proposed biological factors are true by default until proven wrong, that is not scientific thinking.

Wheels Of Confusion wrote:

and at the same time the pattern of occurrence for homosexuality is not consistent with it being purely psychological, and definitely not consistent with it being a choice

Now tell me, who is clinging to a belief in the face of evidence here?

As far as I can tell, you are the only one doing this, I am not proposing any specific theories since none of them have entirely solid ground to stand on, since there is no conclusive evidence for any genetic, hormonal, environmental or biological causes, I am not clinging to any beliefs against any evidence.

Eider wrote:

Lack of evidence for one conclusion never actually lends support to a competing conclusion, especially when the competing conclusion lacks a lot of supporting evidence itself.

You assume I am supporting a competing conclusion when I am not, considering that, most of your argument is wasted. Neither conclusion has enough (or any) conclusive evidence to be considered a default and rule out all others, and much of the evidence that does exist is inconclusive or conflicting.

Burden of proof fallacy, Your logic is that it is, by default, biological until every possibility is ruled out and that all proposed biological factors are true by default until proven wrong, that is not scientific thinking.

Actually, no. You seem to be having some difficulty with this but it's not that hard. I'm saying that biology-based explanations are the most promising, and several commonly-cited non-biology explanations have already been eliminated. There is evidence FOR a biological basis, as in the way homosexuality occurs in the numbers it does and without any obvious psychological baggage. You might take some time to read the links I've provided and learn why I say this instead of ignoring what I've cited and inventing your own argument, an argument that I'm not really making.

I didn't say it was purely biological and I didn't say it wasn't partially environmental. Those two are not mutually exclusive. Environmental factors can have a biological determinacy effect. Again, stop and take a few minutes to read what I'm actually saying.

Lack of evidence where we would expect to find evidence if an idea is true is itself pretty strong evidence that the idea is wrong. This is how pretty much all ideas are tested in science. If the explanation (homosexuality being a choice, for example) does not fit the evidence (the prevalence and psychology of homosexuals), we can consider the idea falsified and move on.

Quote:

Wheels Of Confusion wrote:

Now tell me, who is clinging to a belief in the face of evidence here?

As far as I can tell, you are the only one doing this...

That'd be a neat trick since you can't even tell me what I'm doing. When you've tried, you've been wrong.

That's a nice, subtle ad hominem you have there, but in elementary school science the purpose of the experiment is to determine if the hypothesis is correct, which means you have to entertain the possibility that it is not, instead of modifying the experiment until it shows your desired outcome.

And?

Quote:

Current science shows that there is no conclusive biological cause that can be demonstrated, as of now it seems to simply hang on beliefs, beliefs which seem to of birthed the epigenetic hypothesis, and if it turns out to be incorrect, it will simply be replaced yet with another hypothesis in an attempt to prove it by other means.

It's not "simply out of belief." There are good reasons to attribute at least some of the influence on orientation to biology. Specific mechanisms (like SNPs, or the simplest genetic variations) have pretty much been ruled out, and some other mechanisms have been shown not to work. But not every possible biological factor has been, and at the same time the pattern of occurrence for homosexuality is not consistent with it being purely psychological, and definitely not consistent with it being a choice. Those possibilities have already been pretty thoroughly eliminated, unlike the myriad proposed biological factors. Now tell me, who is clinging to a belief in the face of evidence here?

Burden of proof fallacy, Your logic is that it is, by default, biological until every possibility is ruled out and that all proposed biological factors are true by default until proven wrong, that is not scientific thinking.

Wheels Of Confusion wrote:

and at the same time the pattern of occurrence for homosexuality is not consistent with it being purely psychological, and definitely not consistent with it being a choice

First, what is your definition for a "biological" cause to homosexuality? Biological is a very encompassing term. Many psychological causes, and environmental causes will still be biological. None of these terms are separate from one another.

Wheels Of Confusion wrote:

Now tell me, who is clinging to a belief in the face of evidence here?

Donte wrote:

As far as I can tell, you are the only one doing this, I am not proposing any specific theories since none of them have entirely solid ground to stand on, since there is no conclusive evidence for any genetic, hormonal, environmental or biological causes, I am not clinging to any beliefs against any evidence.

Eider wrote:

Lack of evidence for one conclusion never actually lends support to a competing conclusion, especially when the competing conclusion lacks a lot of supporting evidence itself.

Donte wrote:

You assume I am supporting a competing conclusion when I am not, considering that, most of your argument is wasted. Neither conclusion has enough (or any) conclusive evidence to be considered a default and rule out all others, and much of the evidence that does exist is inconclusive or conflicting.

Lack of conclusive evidence would lead a person to supporting the conclusion that has the most evidence. So far a lot of evidence points to the conclusion that at least a lot of people cannot change their sexuality. This leads to a guess that the cause is biological, and once again this is still an incredibly broad category. It is also possible that there can be more than one mechanism leading to a person's sexuality. Not accepting evidence just because it isn't "conclusive" won't get you anywhere. You at least have to follow the trail where it is pointing to, and a lot of researchers are trying that.

Sorry Boskone, my father was an electrician by trade and a very, very good one. He also happened to be color blind and left handed. It turns out that if you are color blind and can't tell a brown wire from a red wire, you actually trace both wires out just so you know exactly where they are going. My dad did this time and again and never was shocked due to his diligence.

That's wonderful for your dad.

However, some of us are in occupations a bit more demanding than just being an electrician. Now, if he ever tried to troubleshoot a 100kVA generator in the pouring rain, with an entire enterprise waiting on him, then he could try tracing every line individually.

I think you are making assumptions about my dad "just being an electrician." He got his start at the Jim Bridger Coal mine in Wyoming in the late 70's. He became the head electrician of the strip mine. Was in charge of all the power distribution to the huge drag lines and power shovels which requires dealing with 100kV distribution systems on a daily basis. As the drag lines themselves each require 22kV just to operate a single machine. He connected power directly from the power plant out to the strip mine. I think that was a bit demanding electrically speaking, just saying.

I'm sure he was a great. But he was still just an electrician.

When I look at wires, they may be electrical supply, signaling, or data. I may, in fact, be looking at all three while trying to figure out what's up with a satellite dish, after driving 30-odd hours to a disaster site and helping set up a couple hundred servers and a couple hundred user seats, all with a client breathing down my neck because they're losing money.

And colorblindness is a problem of varying degrees of severity for most men, and a significant percentage of women. Try troubleshooting a switch when the green and amber lights look about the same to you, or even just selecting clothing when all dark colors tend towards blue for you. It's also one we know where to fix; we just haven't figured out specifically how. Fix the gene, fix a lot people.

My initial point is that there's a lot of research going into figuring out what genes cause or contribute to problems, but it doesn't seem like there's as much going into figuring out how to repair the genes.

As a gay man I feel very uneasy about any research concerning the causes of homosexuality. I can't help thinking that it might funded by homophobic lobby in order to be able to eliminate homosexuality in the future generations.

On a less paranoid note, my homosexuality on it's own was never a cause of any problems for me - but homophobia of others was. Shouldn't that be the main target of any research instead?I tend to think of being gay as an equivalent of being left handed - a variant of the normal. And I don't think anyone would want to fix that, right?

A good comparison I'd look at is the "God gene" thing that cycles around. Someone like Dawkin's uses it as "you're all just hard coded to believe in God", a religious person may use it as "see? God made us to believe in him". It'll only go the way you suggest if society goes that way itself, a mass cleansing to make a generic human. Which I don't think will happen anytime soon, even if it might happen to screen for major disorders.

There is always the concern that if we get to the point where parents can handpick the genes, they're probably going to want grandchildren. However at that point, a gay couple could probably just have a vat baby anyway, so there's not a whole lot of concern there either. But this is something future generations are going to have to deal with regardless of this kind of research, we're going to figure more out about our genes, we might as well research this divisive issue upfront and come to terms with it early on rather than later.

It'll only go the way you suggest if society goes that way itself, a mass cleansing to make a generic human. Which I don't think will happen anytime soon, even if it might happen to screen for major disorders.

The problem is that for the homophobes homosexuality *is* the major disorder - so if any genetic component of homosexuality is found, it will be an immediate target for them. I'd reckon they will "suddenly" become pro-choice in this case.

A good comparison I'd look at is the "God gene" thing that cycles around. Someone like Dawkin's uses it as "you're all just hard coded to believe in God", a religious person may use it as "see? God made us to believe in him".

I'm pretty sure Dawkins' position is much more nuanced than that. From what I've read he puts stock in a heritable trait that makes people more likely to be religious, but is not simply deterministic or "hard-coded" religiousness. Otherwise he wouldn't also hold the position that religious beliefs are memes, promoted socially as the subject of indoctrination.

Anyway...I would be interested in more information on how they identified "homosexual" individuals - especially given the social stigma (in a few cultures) of it. ("hey, we are looking for gene samples...are you gay? No? Oh, then we will put your genes into the straight group...")

Also, I am curious if they measured the intensity of it.

Like many traits (allergies, eyesight, strength, heart conditions, etc.) it may exist in degrees.This perhaps could make researching it quite difficult - someone who is bisexual may have a very different genetic print than one who is homosexual or one that is just....say...bi-curious - even if they are genetically controlled.

It should probably be added that 23andMe, in response to a lot of requests, conducted a GWAS on homosexuality, which they presented at ASHG last month. Their sample was >24,000 participants but they were unable to find any significant associations between sexual orientation and SNPs.

There are about 311,591,917 Americans, about 49% of which are male. So about 152,680,039 dudes. Homosexuality is prevalent in the general population at about 2%. That gives us approximately 3,053,600 (rounded off a few ones) homosexual men in the US. Using this quick online calculator, we plug in the total number of gay men in the US (3053600), select the 95% confidence interval, and fill in the sample size (1400). This yields a sampling error of about 2.16%. Using a sample size of 5000 gives us a sampling error of 1.385%, which is not a terribly large improvement. Sampling error is cut by almost half, but it's still a small overall effect. Seems like the sample size is sufficient to give us useful information.

There are about 311,591,917 Americans, about 49% of which are male. So about 152,680,039 dudes. Homosexuality is prevalent in the general population at about 2%. That gives us approximately 3,053,600 (rounded off a few ones) homosexual men in the US. Using this quick online calculator, we plug in the total number of gay men in the US (3053600), select the 95% confidence interval, and fill in the sample size (1400). This yields a sampling error of about 2.16%. Using a sample size of 5000 gives us a sampling error of 1.385%, which is not a terribly large improvement. Sampling error is cut by almost half, but it's still a small overall effect. Seems like the sample size is sufficient to give us useful information.

http://blog.23andme.com/wp-content/uploads/2012/11/Drabant-Poster-v7.pdfIn this table you can see that 9% answered as homosexals only(male). That's very high! Not 2 %.

So plug that figure into the calculator and see what comes out (hah!). 9% of the male population would be 13741203. A sample size of 1400 with the criterion being a 95% confidence interval gives us a sampling error of 2.619%. Using a sample of 5000 instead only lowers the sampling error to 1.386. In other words, they are virtually identical to the sampling errors if we assume a 2% prevalence used instead of 9%.

http://blog.23andme.com/wp-content/uploads/2012/11/Drabant-Poster-v7.pdfIn this table you can see that 9% answered as homosexals only(male). That's very high! Not 2 %.

So plug that figure into the calculator and see what comes out (hah!). 9% of the male population would be 13741203. A sample size of 1400 with the criterion being a 95% confidence interval gives us a sampling error of 2.619%. Using a sample of 5000 instead only lowers the sampling error to 1.386. In other words, they are virtually identical to the sampling errors if we assume a 2% prevalence used instead of 9%.

Look my life is shitas a gay. I'm looking forward to become scientist(biochemist/chemist, genetist, biophysist and neuroscientist). In 2015 I will let sequence my entire genome. And latter I will let sequence my dna by Knome Inc.

And as usual, like everything else in the US, sexuality is shoehorned into a black and white binary selection. Gay or straight, Mac or PC, 99% or 1%, Republican or Democrat (is it any coincidence that nations that are more tolerant of non-heterosexual orientations also have more than a two party system?)

Our closest relatives in the animal kingdom express shameless bisexuality. In humans and bonobo chimps alike, sex isn't just for making babies. There are social, interpersonal reasons why we have sex. I believe the natural sexuality of humans is closer to bisexual, with some greater preference one way or the other (because let's face it, a heterosexual preference is necessary to propagate the species). It's just society's preference for black and white options that ends up socially conditioning us to act solely toward one of what may be many preferences.

Look my life is shitas a gay. I'm looking forward to become scientist(biochemist/chemist, genetist, biophysist and neuroscientist). In 2015 I will let sequence my entire genome. And latter I will let sequence my dna by Knome Inc.

Kate Shaw Yoshida / Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas.